Val, a fully grown male chimpanzee, is seen showcasing the ‘grass-in-ear’ behavior at the Chimfunshi Wildlife Orphanage Trust. Chimpanzees residing in a sanctuary in Africa have embraced a unique “fashion trend” of adorning blades of grass or sticks from their earholes and rear ends, as revealed in a recent study. Researchers at the Chimfunshi Wildlife Orphanage Trust chimpanzee sanctuary in Zambia observed this behavior originating from a female chimp in 2010, which was then mimicked by other group members, according to study lead author Ed van Leeuwen, an assistant professor of behavioral biology at Utrecht University in the Netherlands. The behavior did not appear to be linked to pain relief or itching, as the chimpanzees displayed a calm demeanor while engaging in this activity. Van Leeuwen suggested that this behavior could be seen as more of a “fashion trend or social tradition.” Interestingly, a separate group of chimpanzees in the sanctuary began exhibiting the same behavior over a decade later, including the insertion of objects into their rectums. As this second group resided around nine miles away from the initial group, it was unlikely that they had learned it by imitation, prompting Van Leeuwen to consider whether the behavior was influenced by the caregivers. It was discovered that the caregivers in one area of the sanctuary had a practice of cleaning their ears with matchsticks or twigs, which may have been adopted by the chimpanzees and passed on to other group members. Van Leeuwen identified this trend as an example of social learning going viral. He also discussed a similar behavior observed in a group of chimpanzees in a zoo in the Netherlands, where mimicry played a role in social integration. Van Leeuwen emphasized that these behaviors among chimpanzees are driven by a desire to fit in and maintain social harmony, likening these dynamics to human social interactions. The grass behavior was predominantly observed during leisure time when the chimpanzees gathered for grooming and play sessions. In the sanctuary setting, where predators and inter-group competition are absent, chimpanzees have ample leisure time. While wild chimpanzees may also be capable of developing such behaviors, further research is needed to explore their potential for cultural innovation. Van Leeuwen’s future studies aim to investigate chimpanzees’ ability to innovate new foraging techniques and to determine if they can exhibit cumulative culture, similar to humans.
According to a researcher not part of the study, speaking to CNN, these types of observations are crucial for enhancing our knowledge of the beginnings and spread of cultural behaviors in chimpanzees and other non-human animals. She expressed amazement at the study’s discovery of potential interspecies imitation between chimps and their human caregivers. She raised the intriguing question of whether chimps might also learn from and imitate other non-human species. This development is seen as a significant and thrilling moment in the field of primatology. To access more news and newsletters from CNN, you can sign up for an account at CNN.com.
